This invention relates generally to a cleaning apparatus in an electrostatographic machine, and more particularly concerns a foam roll cleaner.
Foam roll cleaners have been used in the past to clean photoreceptor surfaces, because of their low abrasion against the photoreceptor surface, by bringing the foam roll into interfering contact with the photoreceptor and rotating the foam roll against the direction of photoreceptor motion. Toner cleaned by the foam roll is then removed by the action of a flicker bar interfering with the foam roll and an air flow to remove the dislodged particles from the cleaner. However, the foam roll cleaners presently used have limited control in changing environments (e.g. humidity and surface triboelectric conditions).
Electrostatic brush cleaners have advantages over mechanical brush cleaners in that the electrostatic forces used to remove toner from the photoreceptor are much more controlled and predictable, e.g., with respect to environmental conditions. However, one major problem with electrostatic brush cleaners, is that they accumulate toner deep within the brush fibers where the normal detoning methods cannot remove it. This toner accumulation does not normally result in a direct loss of photoreceptor cleaning, but rather in the creation of large spot defects on the copy due to toner dropping or falling from the brush fibers. Another problem with toner accumulation is that toner can accumulate to such an extent that the brush becomes hard and causes mechanical failures. This problem of toner accumulation has resulted in additional detoning devices, in conjunction with the initial detoning devices, being added to electrostatic brush cleaners. Such additional detoning devices for electrostatic brush cleaners include: air detoning to extract more of the toner from the brush cleaner than the original detoning rolls can remove or vacuuming of the electrostatic brushes by technical representatives at regular intervals to avoid excessive toner accumulation.
The following disclosures may be relevant to various aspects of the present invention and may be briefly summarized as follows:
U.S. Pat. No. 3,848,994 to Fraser discloses an electrostatographic system in which dry imaging toner is cleaned from a photoreceptor surface by a soft cleaning member, and the cleaning member in turn is electrostatically cleaned by a secondary or pick-off roller having a multiplicity of closely adjacent and differently charged conductors, which attract toner particles of either polarity and also uncharged toner.
U.S. Pat. No. 3,807,853 to Hudson discloses an apparatus for cleaning electrostatographic imaging surfaces. A cleaning device in the form of a roller that includes a non-conductive cellular surfaced material suitable for removal of marking material from an imaging surface. The roller surface is positioned with its long axis transverse to the direction of movement of the imaging surface and transported over an area of sweeping engagement with the imaging surface. The outer surface of the roller has a plurality of open cells which entrap the excess material on the imaging surface during the sweeping engagement thereof. After engagement, the roller is brought into proximity with a removal device for removing marking material from the surface cells.
U.S. Pat. No. 3,728,016 to Harbour, Jr. et al. discloses a cleaning apparatus for cleaning the residual toner image from an electrostatic plate of an electrostatic reproduction apparatus incorporates an open celled foam wiper which is mounted for wiping engagement with the plate. The foam wiper is mounted adjacent a conductor which is biased to attract charged toner particles to the wiper as the toner image moves relative therepast. The wiper is periodically cleaned by a serrated or grooved portion of the plate which follows the image and mechanically dislodges toner from the wiper. A reverse bias is applied to the conductor as the serrations on the plate move past the wiper creating a field between the wiper and the plate which repels toner from the wiper to the plate. The toner is carried by the serrations on the plate to the developer unit for use by the electrostatic reproduction apparatus.
U.S. Pat. No. 3,656,200 to Riley, Jr. discloses an improved cleaning mechanism for removing contaminants from generally non-porous surfaces. A sponge-like member surrounds a hollow perforated core. Sprayers, internal to the core, spray liquids under pressure to aid in removing contaminants from the sponge-like member against the core at a position where an internal baffle strip contacts the core. This seals the squeezed sponge-like member at the core preventing liquids and contaminants from passing the seal barrier formed.